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Improving IAQ in Schools Series

National School Boards Association & Go Green Initiative

July 15, 2025

Boston Public Schools:

Leaders in IAQ Monitoring

Katherine H. Walsh

Assistant Director of Planning, Engineering, Sustainability, and Environment for Boston Public Schools

M. Patricia Fabian

Associate Professor of Environmental Health and Associate Director �for the Institute for Global Sustainability at Boston University

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BOSTON PUBLIC SCHOOLS

Oldest public school system in the U.S.�
Serves 48,593 students and 11,720 staff in 119 schools from pre-kindergarten to 12^th grade �
Student demographics:

43% Latinx, 29% African American/Black, 15% not Hispanic White, 9% Asian, 3.5% multi-race and 0.5% Native American or Native Hawaiian/Pacific Islander
71% low-income
48% first language not English �

11.6 million sq. ft, 132 Buildings:

50% built before 1950, and 73% built before 1970
30% percent of the school buildings use HVAC for heating and cooling; 70% use steam heat with �limited or no ventilation or cooling �

FY25 District Budget: $1.5 Billion

Boston Arts Academy

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WHO, WHY, & HOW

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BPS School Buildings as

Living Laboratories:

“‘living laboratories’ merge academics and campus facilities management to provide students with real-world skills and, for the institution, �a path to meet its sustainability goals.”

-The Campus as a Living Laboratory

BPS School Buildings as

the Third Teacher:

“There are three teachers of children: �adults, other children, and �their physical environment.”

-Loris Malaguzzi

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LEADING BY EXAMPLE

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Annual School Environmental Audits

One conducted by the BPS Environmental Division
One conducted by the Boston Public Health Commission

Preventative Maintenance and Repairs of Buildings

Operations, Maintenance, Repairs of HVAC Equipment and Systems

Indoor Air Quality Monitoring and Reporting

Asbestos Hazard Emergency Response Act (AHERA) Management

Temperature Monitoring and Control�
Mold and Moisture Control

Integrated Pest Management (IPM)�
Cleaning�
Chemical Management

Waste Management

Anti-Idling

Tobacco and Nicotine-Free Environment Policy

BPS INDOOR AIR QUALITY MANAGEMENT PROGRAM -

A LAYERED RISK REDUCTION APPROACH

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BPS IAQ MONITORING SYSTEM

Why did BPS install Indoor Air Quality Sensors?

Monitoring & Reporting Risk Reduction Layer�Collect, monitor, measure, and evaluate IAQ data in order to:

Prioritize decision-making.
Take appropriate action, such as implementing IAQ interventions or adjusting ventilation rates.
Develop IAQ standards and secure investments that improve IAQ and ventilation.
Communicate and educate about IAQ.
Develop community agency, collaboration, and trust around BPS schools’ indoor environmental quality.

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BPS IAQ MONITORING SYSTEM

https://www.epa.gov/iaq-schools/framework-effective-school-iaq-management

~4,500 IAQ sensors�launched Fall 2021

EPA Tools for Schools

Indoor

Outdoor

= billions of data�points

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WHAT ARE SOME SUCCESSFUL OUTCOMES?

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IAQ MANAGEMENT & RESPONSE ACTION PLANS

EXISTING CULTURE & EXPECTATIONS

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USING IAQ DATA IN BPS OPERATIONS

Monitor and make timely temperature and ventilation adjustments in classrooms. Identify and make repairs with existing HVAC systems.�
Monitor and respond to issues of concern like re-entrainment of CO from co-gen, elevated PM from nearby construction or house fire, elevated CO2 due to poor ventilation.�
Make decisions about school and program closures during extreme heat and cold events.�
Update policies and practices within the BPS IAQ Management Plan and HVAC Maintenance Protocols.�
Enforce district anti-idling and green cleaner policies.�
Educate BPS community about IAQ in their schools.

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INVESTMENTS, INFLUENCE, & RECOGNITION

New Environmental, HVAC, and Mechanical Engineer FTE.�
Facilities staff training related to IAQ.�
Secured ESSER funds to upgrade the Building Management System (BMS) and connect the IAQ sensors to expand demand control ventilation.�
Influence district and City of Boston decision-making about the operations, maintenance, and repairs, and capital design and construction for BPS buildings and systems.

E.g. IAQ design requirements for new construction and major renovations.�

Sharing our story globally, and influencing technical assistance, policy, and funding for K-12 schools.

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JOSIAH QUINCY UPPER SCHOOL

Certified LEED Platinum

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HEALTH &

SUSTAINABILITY

AT

JQUS

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RECENT RECOGNITION & FUNDING

$5M MassCEC Green School Works Grant (2025)

$1.52M MassCEC Green School Works Grant (2025)

$50,000 NSBA & Go Green Initiative IAQ Grant (2025)�
Josiah Quincy Upper School certified LEED Platinum (2025)

Best of Green Schools - District Award from U.S. Green

Building Council (2024)

Best in Class – Energy Efficiency Plus Health from the

U.S. Department of Energy Efficient and Healthy Schools Campaign (2023)

U.S. Department of Education Green Ribbon School District Sustainability Award (2023)

$15.4M IVAQ grant from DESE for HVAC investments (2022)

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Research partnership with Boston University School of Public Health:

“Understanding indoor air quality, thermal comfort, and energy use in classrooms, and the impact of SARS-CoV-2 engineering controls, a pilot study.”

Initial proposal approved 4/29/22

Goal: Create a database of indoor environmental quality, classroom, building, SARS-CoV-2 interventions and occupant behavior data that can be used:��1) as a basis for research grants to understand drivers and modifiers of healthy indoor air quality in BPS schools, and� �2) to support BPS, particularly Operations and Capital, decisions and policies around indoor air quality, thermal comfort, and SARS-CoV-2.

Continuation approved 6/15/25

Goal: Link the IEQ database described above to student outcome data including absences, asthma visits to the nurse, and infectious disease outbreaks. ��This expanded database will support research queries and grant proposals to conduct epidemiology analyses of the linkages between IEQ and student health, as well as the impacts of health interventions.

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Boston Public Schools – Boston University collaboration

https://www.bu.edu/sph/news/articles/2024/professor-partners-with-boston-public-schools-to-study-classroom-air-quality/

~4,400

IAQ sensors

125

Schools

= billions of data points yearly

DATA

ANALYSIS

DASHBOARD

BPS IEQ system

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Boston Public Schools – Boston University collaboration

Communications
Workshops
Presentations
Grants
Bi-directional education

School operations
Environmental health

IAQ/IEQ data

IAQ DASHBOARD �USER GUIDE

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It starts with IAQ data, plus quality control, plus more data

HVAC

CO2, CO

PM2.5, PM10

Temp, RH

Meteorology

Covid interventions

Neighborhood

Air pollution
Greenspace
Demographics
Segregation
…

Schools

Energy

Researcher tools:

Computing infrastructure
Data science
Geographic Information Systems (GIS)
Environmental health
Building science
Statistics

IAQ

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The value of installing IAQ sensors in every classroom - CO2

Key data takeaways:

High CO2 variability at a classroom level within schools, across schools and over the school year
Captured 98% of days per sensor over a school year (5%-100%)
Processing of CO2 data enhances its value for decisions beyond real-time

Utility:

Prioritize classrooms and schools needing more ventilation
Optimize building maintenance resources
Create baseline metrics to evaluate interventions
Identify seasonal or recurring patterns

Ge et al (2025) Lancet Regional Health: Americas https://doi.org/10.1016/j.lana.2025.101148

CO2 <1000ppm 76% of the time, <2000ppm 98% of the time
During the school year, 3659 classroom sensors collected over 245 million minute-level CO₂ measurements across 125 BPS school buildings. On average, sensors recorded at least one observation during school hours on 95% of days (171 days) throughout the school year (SD: 14% or 25 days). Sensors recorded an average of 92% (SD: 16%; range: 4%-99.99%) of expected observations. 3.5% of entries (9 million) were removed due to being duplicates or having missing CO₂ measurements. Smoothing reduced missingness to 5.3%. Overall, there was no systematic change in missingness over the school year.
On average, 0.3% (SD: 1.2%, range: 0–23%) of each sensor’s 15-min rolling median daytime CO₂ measurements were excluded due to falling outside the filtering range. Restricting to complete days of data resulted in an average retention of 98% of days per sensor (SD: 6%; range: 5%–100%). Supplemental Fig. S2 demonstrates how data completeness varies across a sample of 20 random schools over the school year.

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The value of installing IAQ sensors in every classroom - CO2

Key data takeaways:

High CO2 variability at a classroom level within schools, across schools and over the school year
Captured 98% of days per sensor over a school year (5%-100%)
Processing of CO2 data enhances its value for decisions beyond real-time

Utility:

Prioritize classrooms and schools needing more ventilation
Optimize building maintenance resources
Create baseline metrics to evaluate interventions
Identify seasonal or recurring patterns

Ge et al (2025) Lancet Regional Health: Americas https://doi.org/10.1016/j.lana.2025.101148

Blue – low CO2

Yellow – high CO2

Gray - missing

White - holiday

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The role of ventilation in reducing CO2

Key data takeaways:

Lower CO2 in schools with mechanical vs natural ventilation (930 ppm vs 698 ppm on average)
CO2 elevated at times in all schools
Demand-control ventilation (DCV) most effective system (99% of CO2 measurements <1000 ppm)

Utility:

Advocate for system upgrades
Optimize HVAC system maintenance
Identify schools to connect to building management systems (BMS)
Improve vendor accountability

Ge et al (2025) Lancet Regional Health: Americas https://doi.org/10.1016/j.lana.2025.101148

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How many IAQ sensors does a school need?

Key takeaway:

The larger the school the more sensors are needed

>5 for schools with ≤15 classrooms
15 for schools with 16–30 classrooms
20 for schools with 31–45 classrooms
25 for schools with 46–75 classrooms
>25 for schools with 76-150 classrooms

Utility:

Capture the IAQ landscape of a school with limited budget

Figure S4. Box plots showing the absolute percent difference between the classroom sensor sample mean and the school building mean for different sizes of sensor samples, stratified by building size.

Ge et al (2025) Lancet Regional Health: Americas https://doi.org/10.1016/j.lana.2025.101148

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New methods to measure ventilation using CO2

https://www.bu.edu/sph/news/articles/2025/fresher-air-smarter-schools-sph-researchers-share-novel-method-for-monitoring-indoor-air-quality/

Yuan et al (2025), Indoor Environments 10.1016/j.indenv.2025.100083

Old method - spot check with balometer

New method - daily AER estimate with

IAQ sensors + machine learning

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The value of installing IAQ sensors in every classroom - heat

Key takeaways:

Temperature variability between classrooms in the same building:

2.3°C on average
14.4°C max difference in buildings without mechanical cooling
6°C cooler at ground level compared to upper level in buildings without mechanical cooling

Central and window AC maintained comfortable temperatures compared to buildings without mechanical cooling.
Novel temperature metrics captured heat frequency, intensity and length - different from maximum temperature

Utility:

Identify cooling needs and prioritize investments
Inform heat action plans
Evaluate interventions
Identify seasonal or recurring patterns
Justify mechanical cooling investments in Northeast US

Botana et al (2025) Indoor Environments https://doi.org/10.1016/j.indenv.2025.100105

School A

All classrooms

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Predicting mold growth with temperature and relative humidity

Utility:

Monitor classrooms during periods of school shut down (i.e., summer)
Direct resources to prevent larger problems

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A reminder about why we care about IAQ/IEQ

https://arcg.is/1rG58m1

If you ever felt stuffy, hot, smelly and like the AC didn’t cool or the furnace didn’t heat – you were exposed to indoor environmental quality

So, to recap, we’ve established that many school building in the US are in poor condition. And there is a lot of evidence connecting building conditions to indoor environmental quality and building energy consumption which in turn impact learning and health. How IEQ and energy changes impact health and learning is complicated but I can tell you there is a lot of literature supporting these links. Very high level you can see from the graph some examples of indoor environmental stressors in red. These can impact learning directly but also indirectly through health and absences pathways, you can see some examples of health impacts in blue. But in the end everything leads to learning. I’m happy to chat more about this later. But the bottom line is the building and building systems affects learning and test scores in complicated ways. Asthma, absences

Mental health includes our emotional, psychological, and social well-being. It affects how we think, feel, and act, an

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ACKNOWLEDGEMENTS

Pilar Botana
Beverly Ge
Yirong Yuan
Priam Vyas
Masanao Yajima
Jinho Lee
Koen Tieskens
Muskaan Khemani
Students: Carmen Zhou, Johnny Rezendes, Talia Feldscher, Kyleigh Gunn, MSSP program
IT & Shared Computing Cluster

Research Funding:

Established Investigator Innovation Award, BU School of Public Health;

Early Stage Urban Research Award, BU Initiative on Cities; Training grants from National Institutes of Health and National Science Foundation

Lauren Main
Lauren Bolton
Kayla Brandt
Rose Rodriguez
Maria Carvalho
Mike DiLorenzo

Ron McMahan
Christopher Schepcoff

Acknowledgements

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Key takeaways about comprehensive IAQ monitoring in schools

Real-time IAQ monitoring in classrooms is useful!
Pinpoint specific times, days and locations where there are problems
Prioritize and optimize resources to improve IAQ
Inform Action Plans (e.g., heat, mold, wildfire smoke, air pollution, IAQ management)
Generate local data necessary to drive action and investment
Limitation - needs technical resources to maximize utility (e.g., data science, environmental health, computing, statistics)

One solution: school-researcher partnerships

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RESOURCES

Boston Public Schools

IAQ Webpage

IAQ Monitoring Dashboard

Healthy School Environment Webpage

IAQ Management Plan

BPS in Center for Green Schools materials

School IAQ Management Plan Toolkit
School IAQ Fact Sheets
Clean Air in Schools Course

Boston University

Publications & reports
Stories, maps and videos
Email for code
https://sites.bu.edu/fabian/chess/

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QUESTIONS?

More information:

Katherine H. Walsh, Boston Public Schools

kwalsh4@bostonpublicschools.org

https://bostongreenschools.org

M. Patricia Fabian, Boston University

pfabian@bu.edu

https://sites.bu.edu/fabian/research/chess

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